50 
Barber —On the Structure and 
cylindrical, and does not greatly increase in thickness. For 
a considerable time, however, it is the longer part of the 
stipes, and not until the bulb has become well attached 
does it lose its importance as the principal fixing organ. 
The portion above the ridge commences very early to 
assume a different form to the lower portion. At a time 
when the ridge itself is hardly perceptible the cells of the 
upper part show a marked difference from those of the 
lower. The central cells have assumed an irregular course, 
and very quickly exhibit the winding, twisted appearance 
of the so-called ‘hyphal tissue.’ At the same time the 
transverse „ section here becomes oval, and the median 
strand of hyphal tissue appears as a line along the greater 
diameter. The stalk then becomes flat and twisted, but 
remains short (Figs. 3, 4). It is not until the bulb is well 
developed that the elongation of the stipes is marked, 
growth taking place at the point of junction of the stalk 
and lamina. A straight, ribbon-shaped piece arises by in- 
tercalary growth between the twisted portion and the lamina 
(Fig. 8). The greatest length that the stalk appears to 
attain is somewhat over two feet, but its length depends 
on the depth of water in which the plant grows 1 . Two 
or three stalks may arise from one bulb. 
This appears to be a not uncommon phenomenon among the Laminarias. Le Jolis 2 
saw several specimens of Z. hyperborea divided dichotomously to the middle or 
base of the stalk; and in Lenormand’s Herbarium he observed a specimen of 
L. digitata bifurcated. Turner 3 has cited a case of Z. digitata forked at the 
summit, each half bearing a lamina : and De la Pylaie 4 mentions a similar case. 
Agardh 5 thinks that the branching is due to a split of the lamina being produced 
downwards into the stalk ; but Le Jolis regards this as impossible, for, in the 
Z. hyperborea examined by him in the living state, there were no signs of tearing. 
From the cases mentioned it appears that the branching of Z. bulbosa is due either 
to a split of the lamina extending down the stalk, or to a real bifurcation of the plant. 
The healing of a split is very readily traced on making a section. It would therefore 
seem probable that the explanation of Le Jolis is the right one. And in this case 
the branching must occur at a very early period owing to the peculiar intercalary 
growth of all these plants. There is, however, a third method by which such 
1 Greville, Algae Britannicae, 1830. 2 Nov. Act. Acad. Leop. Car. xxv. 1855. 
3 Hist. Fuc. t. iii. p. 68. 4 Flore de Terre Neuve, p. 24. 
5 Sp. Alg. i. 135. 
